The 62-year-old retired teacher called the Sheriff's Department last Friday to say he was lost.
Dispatchers lost contact with Christy on Saturday.
Rangers at Yosemite have rescued several people from the cold, wet conditions this winter.
The pristine powder that now covers Yosemite's slopes is a strong draw for skiers and snowshoers.
Jeff Techau, Yosemite Visitor: "We came up with a group from San Luis Obispo area, we've been up here for two days, just having a lot of fun in the snow."
But the winter weather can also be dangerous and potentially deadly.
"We get between two and 300 rescues in Yosemite every year."
Park Ranger Nate Knight says people often have unrealistic expectations about how far they can travel through the thick snow and end up stranded in unfamiliar territory.
Nate Knight: "One of the main things that gets people in trouble is pushing themselves into areas where they shouldn't have gone."
When that happens Knight says drivers should wait for help in their cars. But hikers need to find another source of shelter, like the wells that can form at the base of a tree.
Nate Knight: "I've already got some walls, I've got a bit of a roof, I'm going to put this over the top of me to keep out a little more moisture, hold in a little more heat, and I'm ready to go for awhile. It won't be comfortable, but I'll live til the morning."
Another option is to use a ski or snowshoe to dig a shelter in the snow.
A snow cave like this can keep you dry and relatively warm overnight. Even when the temperature is zero degrees Fahrenheit outside, it will stay about 32 degrees in here."
But rangers say the most important steps for survival come before you even leave home. Knight suggests packing a bag with all of the essentials, like food, water, and a map plus some simple items that can help search teams find you like a CD to use as signaling device and a whistle to call for help.
"Three blasts is typically a sign of distress."
And Knight says be sure to tell someone your specific plans before wandering out into the high country.
